在Javascript中，所有内置对象都是不可变的吗？

Question

I know that String and Number objects are immutable but are all built-in objects immutable as well? If it's not true, can you give me an example of a built-in object that is mutable?

Answer 1

Arrays are mutable. Here are a list of mutable methods for arrays.

push - Elements are added on to the end of the array

pop - Elements are removed from the end of the array

shift - Elements are removed from the beginning of the array

unshift - Elements are added to the beginning of the array

splice - Adds/removes elements to an array

None of these methods create a new array, but modify the existing array.

Answer 2

Nope, for instance an array is mutable. If you have an array of strings and you push a string to it, you don't get a new array with an extra string added to it. The original array is altered.